Phnom Penh (Agencies): Thai and Cambodian troops clashed on Monday for a fourth straight day, Cambodian Prime Minister Hun Sen said, as tensions again surged in a border dispute that has left at least five people dead.

"The firing has started for the fourth time," Hun Sen revealed at a graduation ceremony in the capital.

A Cambodian military commander said on condition of anonymity that both sides traded fire just after 8:00 in the morning (local time). He was unable to say what kinds of weapons were involved.

A Thai military source near the border said that about two minutes of small arms fire had been heard on Monday morning, describing it as a "misunderstanding".